Various abbreviations that appear in the specification and/or in the drawing figures are defined as follows:    AP access point    BS base station (network access node)    CP cyclic prefix    DRX discontinuous reception    DTX discontinuous transmission    GPS global positioning system    LTE long term evolution (evolved or E-UTRAN, e.g., Rel. 8)    LTE-A LTE advanced    MIMO multiple input/multiple output    O&M operations and maintenance    OTA over-the-air    SFN system frame number    SON self-optimizing network    TDD time division duplex    UMTS universal mobile telecommunications system    UTRAN UMTS terrestrial radio access network
In wireless networks it is often the case that all network nodes agree on when a new time period begins, which implies that the beginning and the end of the time period for the nodes needs to be synchronized in some manner.